Someone who overuses or misuses a keyboard or keypad to enter data into an electronic device may be subject to orthopedic problems known generally as repetitive-motion or repetitive-use injuries. Such injuries reportedly may become more likely as the size of the keyboard or keypad decreases. For example, users may respond to ergonomic challenges presented by some very small keypads by entering data using only their thumbs, thereby risking inflammation of the sheath around the tendons of the thumbs if the keypad is used excessively.
Nevertheless, small electronic devices such as personal digital assistants, cellular telephones, and laptop computers have become extremely versatile, and may offer a wide variety of applications to the user. Consequently, approaches to guarding against repetitive-motion injuries developed for single-application devices such as typewriters are not necessarily suitable for modern multi-application electronic devices, since the user may interact with the multi-application device in different ways when using it for different applications.